Steam-based electric power plant operated on renewable energy

ABSTRACT

A system, apparatus and method for generating electricity from renewable geothermal, wind, and solar energy sources includes a heat balancer for supplementing and regulating the heat energy fed to a turbine generator; a hydrogen-fired boiler for supplying supplementary heat; and an injection manifold for metering controlled amounts of superheated combustible gas into the working fluids to optimize efficiency. 
     Wind or solar power may be converted to hydrogen in an electrolysis unit to produce hydrogen. A phase separator unit that operates by cavitation of the geothermal fluids removes gases from the source fluid. A pollution prevention trap may be used to remove solids and other unneeded constituents of the geothermal fluids to be stored or processed in a solution mining unit for reuse or sale. Spent geothermal and working fluids may be processed and injected into the geothermal strata to aid in maintaining its temperature or in solution mining of elements in the lithosphere.

CROSS REFERENCE TO RELATED APPLICATIONS

The present U.S. Patent Application is related to the following U.S.Patent Applications entitled: Renewable Energy Electric GeneratingSystem, U.S. patent application Ser. No. 12/333,513, filed Dec. 12,2008, now U.S. Pat. No. 8,169,101, issued May 1, 2012; Heat Balancer forSteam-based Generating Systems, U.S. patent application Ser. No.12/333,536, filed Dec. 12, 2008; Cavitation Phase Separators forSteam-based Generating Systems, U.S. patent application Ser. No.12/333,549, filed Dec. 12, 2008; and Methods for Enhancing Efficiency ofSteam-Based Generating Systems, U.S. patent application Ser. No.12/333,658, filed Dec. 12, 2008. The present and foregoing relatedpatent applications claim priority from U.S. Provisional PatentApplication No. 61/090,092, filed Aug. 19, 2008 and entitled ElectricPower Generation System Utilizing Multiple Renewable Energy Resources,by the same inventors.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to electric power generationusing renewable sources of energy, and more particularly to enhanceduses of wind or solar energy in combination with geothermal fluidsoriginating in hot strata of the earth's mantle as a source of heat foroperating steam-driven turbine generators. The system, apparatus, andmethods disclosed herein utilize wind or solar generated electricity,hydrogen gas, and optimized parameter control to exploit the heat energyavailable from geothermal fluids in providing efficient generation ofelectric power with a very low carbon footprint and near zero emissionsinto the atmosphere.

2. Background of the Invention and Description of the Prior Art

Use of the heat energy in geothermal fluids such as dry or wet steamfrom deep production wells into the earth's mantle (“hydrothermalresources,” as described in an article entitled Geothermal PowerStations, by Lucien Y. Bronicki, in the Encyclopedia of Physical Scienceand Technology, Third Edition, 2002, Robert A, Meyers, Editor-in-Chief,Volume 6, pp. 709-719) as a source of heat to drive steam turbineelectric generators is an active area for renewable energy developmentand research. Conventional approaches endeavor to extract as much heatenergy as possible from the geothermal fluids before returning them viainjection to locations beneath the surface of the earth where the fluidsmay reacquire heat energy from the hot rock strata.

Conventional electric generating facilities such as natural gas-fired orcoal-fired generators are of questionable utility to meet futureelectricity needs because they burn carbon based “fossil” fuels andoxygen. In addition to having a large and undesirable carbon“footprint,” such facilities produce as undesirable byproducts carbondioxide and nitrous oxide, believed to be among the principlecontributors to climate change and air pollution. In addition, thesefossil fuel generating facilities are expensive to construct.Nuclear-fueled generators, though having a small carbon footprint andlow atmospheric emissions, are extremely expensive to build and operate,and present the additional problems of disposing of the nuclear waste.Nuclear power generating plants are also faced with dissipating largeamounts of waste heat. Thus, the prospects of relying on fossil fueledor nuclear fueled electric power plants to meet the future electricityneeds of a growing population with minimal effects on the earth'senvironment at a reasonable cost are unpromising. New ways of generatingand distributing electric power must be developed and made available tothe distribution grids.

In looking to other sources of energy for generating electricity,particularly renewable sources, one must keep in kind that there aremany variables in the generation and distribution of electric power.Demand peaks and ebbs in response to temporal and climate cycles. Theoutput of wind powered generators as shown in FIG. 1 is subject to videvariations in climate conditions. Moreover, the temperature and heatcontent of geothermal fluids—principally steam, but may also includewater and brine solutions of varying composition—varies widely accordingto geographic and geological diversity, as well as the depth andsuitability of production wells. While advances are being made inharnessing the extremely abundant solar energy, inefficiencies andproblems of scale continue to challenge development efforts.

In FIG. 1, there is illustrated in simplified form a conventionalwind-powered electric generator system 10 that is typical of the priorart. In the system 10, an electric generator 12 is rotated by awind-driven propeller 14 to generate an electric voltage that isconducted to a distribution grid 16 (not shown) along wires 18. Thewires 18 may typically be supported by a plurality of towers 20 spacedat substantially uniform distances to connect the generator output tothe distribution grid 16. In a typical wind farm, many such windgenerator systems 10 may be employed, their outputs coupled to thedistribution grid via direct wires 18 as shown or via wires to asubstation (not shown, because it is well known in the art), which inturn may be connected to the distribution grid 16. The elements of sucha wind power generating system 10 and distribution grid 16 are wellknown and will not be further described herein.

In a basic, prior art electric power plant that utilizes geothermalfluids, one example of which is shown in simplified form in FIG. 2, drysteam or high temperature water from geothermal production wells is usedto drive a steam turbine and electric generator. The geothermal fluidfor use as a working fluid to drive a turbine may be obtained from anydeep natural gas, oil, water, geothermal well, etc. having sufficientheat at depth. Note that a working fluid in this context may be either aliquid or a vapor (such as dry steam). In a dry steam plant, the turbineis driven directly by the geothermal steam. In a flash steam plant, hightemperature fluids are first vaporized in an expansion chamber at lowpressure and the water vapor is used as a working fluid to drive theturbine. Since many production wells produce geothermal fluids ofmoderate temperature, e.g., less than 200° C., the geothermal fluid maybe routed through the primary side of a closed heat exchanger in a thirdtype of power plant called a binary-cycle power plant.

In a binary cycle geothermal power plant, illustrated in basic form inFIG. 2, a second working fluid, such as an organic working fluid thatboils at a lower temperature than water, is conducted through thesecondary side of the heat exchanger. A few examples of organic workingfluids include ammonia, isopentane, isobutane, etc. Heat from theprimary side geothermal fluid is transferred to the secondary “organic”working fluid that is used to drive the turbine. A given geothermalpower plant may employ one or more turbine/generator combinations. Theoutput of the generator is connected to an electricity grid fordistribution and the spent steam is typically injected into the earthvia an injection well.

The system 30 shown in FIG. 2 includes an electric generator 32 whoseelectric output is coupled to the distribution grid 16 via wires 34. Thegenerator receives its driving force from the rotating output shaft 38of a steam driven turbine 36. The steam driven turbine 36, a well-knownstructural component, converts high temperature, high pressure steam tothe mechanical rotation of its output shaft 38. The steam, also calledthe working fluid, is applied to an inlet 40 of the steam turbine 36 viaa conduit 44, which carries the working fluid in a circulating loop. Theworking fluid is chosen to have a lower boiling point than thegeothermal fluid, which most commonly has a temperature between 150° C.to 200° C., although some hydrothermal deposits may range from under100° C. to as high as 350° C. The working fluid receives heat energy bypassing through a heat exchanger 50, where heat is transferred to theworking fluid flowing in conduit 44. This transfer of heat causes theworking fluid to vaporize. In the heat exchanger 50, the hottergeothermal fluid flows through internal passages in close proximity tothe passages conveying the cooler working fluid to facilitate thetransfer of heat into the working fluid. The heat exchanger 50 has asource side 52 and a demand side 54, referring respectively to thesource of heat to operate the turbine and to the loading or demand forelectricity on the output of the generator 32. The geothermal fluid isobtained from deposits 60 via production wells 62 and pumped by a pump64 through a conduit 66 and the source side 52 of the heat exchanger 50.After giving up some of its heat in the heat exchanger 50, the cooledgeothermal fluid is returned to the Earth via a conduit 76 and aninjection well 72 into deposits 70 similar to or adjacent to theoriginal deposits 60.

The use of two separate fluids in the power plant of FIG. 2 enablesisolation of the fluid used to drive the turbine 36 from the fluidproduced from the production wells 62 and thus gives rise to the term“binary cycle” power plant. A binary cycle power plant thus prevents theoften caustic, corrosive, or abrasive substances that may be containedin the geothermal fluid from damaging the internal components of theturbine 36. The working fluid may be water, or low temperature steam, oran organic fluid material such as isobutane, isopentane, propane, orother easier-to-condense hydrocarbons. These organic compounds may beused because of their relatively low boiling points. The geothermalfluid may be high temperature steam, hot water, high temperature brine,a mixture of these fluids, or a mixture containing one or more of theseand other elements, minerals, or hydrocarbon compounds.

While these prior art plants can provide electricity from renewablesources with zero emissions, they are subject to inefficiencies andvariable outputs because of the variability in temperatures of thegeothermal working fluids. Such systems are adequate for steady stateelectricity loads but are much less suited to meeting the demands forboth base loads and peak loads, and levels of demand intermediate baseand peak loading. Accordingly there is a need for electric powergeneration systems that rely on renewable sources and provideelectricity output responsive to wide variations in demand despitepotentially wide variations in the energy resources from which theelectricity is derived. Additionally, it is preferred that the systemoperate with zero emissions into the atmosphere or into the earth'swater resources. Moreover, it is further preferred that the system beconfigured to operate with improved efficiency and to minimize the wasteof heat or unused constituents of the working fluids obtained from thedeep wells or other resources.

SUMMARY OF THE INVENTION

Accordingly, there are disclosed herein a system, apparatus and methodsfor the generation of electricity from geothermal, wind power, and otherrenewable energy resources as supplemented by hydrogen injection andheat balancing to optimize efficiency. In the present invention,hydrogen gas plays a key role in the heat balancing techniques. Further,the system may provide low power recovery of geothermal fluidconstituents for reuse, all while operating with minimal or zeroatmospheric emissions and ground water pollution.

In the systems, apparatus and methods to be described herein severaltechniques are disclosed wherein operating efficiencies can be improveddramatically. One such method is to regulate the density of the workingfluid input to the turbines, thus providing a convenient and effectivemethod of regulating the generator output with respect to the loading ofthe generator. Another is to regulate and provide a constant, optimumtemperature of the working fluid input to the turbines, through the useof novel heat balancers. Another is to provide for removing gases fromthe working fluids through the use of novel cavitation separators. Yetanother is to recycle the working fluids to fully utilize the heatenergy contained within them or return—i.e., inject—the geothermalfluids to be disposed into the Earth's strata. Further, apparatus andmethods are disclosed for recovering unused constituents for reuse orresale, and for reuse or re-balancing spent working fluids to extractuseable energy there from. A typical system may also include a pollutionprevention trap to ensure against release of substances contrary toregulations.

The present invention addresses the many variables mentioned above byexploiting a combination of renewable geothermal, wind power, and solarpower sources. Technology and resources are used in new ways to produceelectricity at low cost, with zero or near zero emissions. The systembalances variations inherently present in geothermal, wind, and solarsources of energy. The system can efficiently respond to variations indemand and temporal and climatic conditions. A further benefit is thelow cost, low power recovery of unused but valuable constituents presentin the geothermal fluids used as a source of heat energy. Theseconstituents may be reused, stored, sold, or injected back into theearth. The system operates closed loop, that is, its apparatus andprocesses are closely regulated and the system gives up little or noenergy or emissions to its surroundings.

Accordingly, it is an object of the present invention to provide anelectric generating system that operates on renewable energy sources toobtain a very small carbon footprint, to operate with very lowemissions, and to provide substantially improved efficiency.

It is a further object of the present invention to provide a moreefficient heat balancing apparatus to improve the transfer of heatenergy and increase the energy content of the working fluids in a binarycycle power plant.

It is further an object of the present invention to provide a heatbalancer that combines an improved heat exchanger and a gas-injectionmanifold to maximize heat transfer from a source fluid to a demand(working) fluid and to enhance the heat energy content of the sourcefluid entering the heat balancer.

It is further an object of the present invention to provide forinjecting a combustible gas such as hydrogen into the steam turbineworking fluid inlet to optimize the energy density of the working fluid.

It is further an object of the present invention to provide a heatbalancing apparatus that minimizes the build up of scale in its internalpassages, thus prolonging the interval between required maintenance.

It is a further object of the present invention to provide an improvedphase separation apparatus that efficiently removes gases from theworking fluids of a binary cycle power plant to maximize the efficiencyof the working fluid and enable recovery of the removed gases for reuse.

It is a further object of the present invention to provide an apparatusand method for injecting combustible gases such as hydrogen into theworking fluid to improve the energy density thereof and to more closelyregulate the energy density and content of the working fluids formaximizing efficiency op operation.

It is a further object of the present invention to provide a combinationof renewable energy sources and programmable control systems to enablean electric generating system to operate at any level from base load topeak load conditions, even when the demand for electricity encounterswide swings because of time of day, climatic conditions, and consumeruses; and even when renewable energy sources are subject to wide swingsin availability because of variations in climate, geographical location,geological temperature conditions, solar radiation, and the like.

It is a further object of the present invention to provide a combinationof apparatus for storing renewable energy such as wind andsolar-generated electricity.

It is further an object of the present invention to provide hydrogengas, from electrolysis of water by renewable energy generatedelectricity, to be stored and utilized to increase the efficacy ofworking fluids and steam turbines; to provide supplemental heat energy,as in a hydrogen-fired boiler to produce hot, dry steam for use in abinary cycle power plant; and to enable restoration of the pH of workingfluids returned to the geothermal strata via injection wells.

It is further an object of the present invention to provide systems andmethods for recovery of elemental constituents of geothermal fluids notneeded for power plant operation for other commercial uses withoutemitting or releasing toxic constituents into the atmosphere orgeological surroundings.

It is a further object of the present invention to provide an improvedbinary cycle power plant system having reversible aspects to enablerecovery and reuse of heat energy remaining in the working fluidscirculating within the closed loop system.

These and other objects are met in the inventions embodied in therenewable energy power plant system, apparatus, and methods disclosed inthe following descriptions. In one aspect, a system is provided forgenerating electricity from a working fluid heated from renewable energysources comprising a geothermal heat exchanger for transferring heatenergy from geothermal fluid to a working fluid; an electrolysis plantfor producing hydrogen gas; a boiler heated by the hydrogen gas toproduce hot steam; a heat balancer for transferring heat from the hotsteam to the working fluid; and a turbine generator that uses theworking fluid to generate electricity. The electrolysis plant may bepowered by electricity generated from a renewable energy source.

In another aspect, a heat balancer for a geothermal steam turbinegenerator comprises a heat exchanger having a plurality of separateinterleaved passages for respectively a source fluid and a demand fluid;a source fluid manifold system coupled between a source fluid inlet andthe respective source fluid passages; and a demand fluid manifold systemcoupled between a demand fluid inlet and the respective demand fluidpassages; wherein the source and demand fluids flow in oppositedirections on respective opposite sides of the plates separating thesource and demand passages. A gas injection manifold system may becoupled between the source fluid inlet and manifold.

In another aspect, a phase separator is provided comprising a pair ofopposing concave half-cylindrical shells; a stacked-elementpiezoelectric transducer coupled between opposing interior surfaces ofthe half-cylindrical shells to cause cavitation of the fluid flowing inthe conduit; a plurality of fluid conduits attached to exterior surfacesof the half-cylindrical shells; and a drive circuit for exciting thepiezoelectric transducer to cause cavitation of the fluid in theconduits. An alternative embodiment provides a phase separatorcomprising a hollow tubular body having a longitudinal gap formed in oneside of the hollow tubular body; a piezoelectric transducer layerlaminated to at least a major portion of the interior surface of thehollow tubular body opposite and symmetrical with respect to the gap; aplurality of fluid conduits attached to exterior surfaces of the hollowtubular body; and a drive circuit for exciting the piezoelectrictransducer to cause cavitation of the fluid in the conduits.

In another aspect, a method for enhancing the efficiency of asteam-driven turbine generator comprises the steps of providing drysteam of a suitable temperature to an inlet to the turbine generator;supplementing at least one operating parameter of the dry steam withhydrogen gas to optimize efficiency of the turbine generator; monitoringthe effect of the at least one operating parameter in the turbinegenerator; and executing one or more program sequences of a controlsystem to adjust the at least one operating parameter of the system inresponse to the monitoring step.

In yet another aspect, an electric power plant utilizing heat energyoriginating as geothermal fluid extracted from a production well todrive a steam-driven turbine generator further comprises ahydrogen-fired boiler to produce hot dry steam to supplement a workingfluid driving the turbine generator; an electrolysis plant to producehydrogen gas to fire the boiler; and a wind powered generator to produceelectricity to operate the electrolysis plant. The power plant mayfurther include a heat balancer, a hydrogen injector for regulating theenergy density of said working fluid, and a piezoelectric cavitationphase separator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a conventional wind-powered electric generator;

FIG. 2 illustrates basic features of a prior art binary cycle geothermalpower plant;

FIG. 3 illustrates one embodiment of a renewable energy power plantaccording to the principles of the present invention;

FIG. 4 illustrates a flow chart diagram of one aspect of the embodimentof FIG. 3;

FIG. 5 illustrates a block diagram of another aspect of the embodimentof FIG. 3;

FIG. 6 illustrates a top side view of a heat balancer apparatus of theembodiment of FIG. 3 having a hydrogen injection manifold coupledthereto and showing paths of flow of geothermal fluids (source circuit)and working fluid (demand circuit) through the heat balancer;

FIG. 7 illustrates a side elevation view of the heat balancer apparatusof FIG. 6;

FIG. 8 illustrates a view of the edge-wise cross section of a platehaving a zig-zag or herringbone pattern as used in the heat balancer ofFIGS. 6 and 7;

FIG. 9 illustrates a simplified perspective view of a basic cavitationphase separator according to the present invention for use in theembodiment of FIG. 3;

FIG. 10 illustrates a simplified perspective view of a portion of afirst embodiment of a piezoelectric cavitation phase separator accordingto the present invention;

FIG. 11 illustrates a cross section view of the embodiment of FIG. 10;

FIG. 12 illustrates a simplified perspective view of a portion of asecond embodiment of a piezoelectric cavitation phase separatoraccording to the present invention;

FIG. 13 illustrates a cross section view of the embodiment of FIG. 12;

FIG. 14 illustrates a simplified block diagram of one embodiment of apollution prevention cold trap according to the present invention; and

FIG. 15 illustrates a simplified block diagram of a programmable controlsystem for use with the embodiment of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

The following descriptions, read in conjunction with the foregoingdrawings, disclose inventions for a system, apparatus, and methods, forgenerating electricity for base through peak load conditions usingrenewable energy sources. The inventions provide renewable energy powerplants that generate electricity without burning carbon-based fuels andwithout emitting harmful chemical compounds into the earth's atmosphere.Principle features of the inventions include:

1) A distributed heat balancing system for generating electric powerusing geothermal fluids and hydrogen as working media, in combinationwith wind or solar power generation and electrolysis;

2) Heat balancing apparatus using a closed, herringbone vane heatexchanger in a counterflow configuration that employs steam produced bya hydrogen-fired boiler to transfer its heat energy to and optimize theheat content of the working fluid or gas;

3) A hydrogen injection apparatus using rare earth magnetostrictive(REM) valve-controlled capillary tubes to enhance the energy content ofthe geothermal working fluids, directly regulate the density of thesteam driving the turbine generators, and to boost the temperature ofthe working fluid being returned via the injection well to the strataproviding the geothermal energy;4) A cavitation phase separator apparatus and method for separating gasconstituents and other materials not chemically bound from geothermalfluids; and5) A computer control system and method for controlling the heatbalancing, hydrogen injection, and other systems in a renewable energypower plant to optimize the operating efficiency of the generatingsystem and to balance the electricity outputs in response to the demandfor power.Introduction

Geothermal energy refers to hot materials obtained from production wellsdrilled into hot strata in the Earth's crust. These hot and, in certainlocations of the Earth's mantle, very plentiful materials may be steam(dry steam), water at a temperature above the boiling point (wet steam),or other fluids such as brines containing mixtures of water, salts,minerals, or gases. The geothermal fluids, brines, and gases aregenerally hot and under substantial pressure. The term “geo-pressuredgas” refers to geothermal gas under pressure in confined spaces in theEarth's crust. The term “geothermal fluid” is a general term referringto any such geothermal material that is brought to the surface for thepurpose of utilizing its heat energy in some useful way. The geothermalfluid has a temperature corresponding to the depth below the surface ofthe Earth at which its deposits exist. The average geothermal gradientis approximately 25° C. per Kilometer of depth. Thus, the range ofdepths of interest as sources for the geothermal fluids to be used ingeothermal power plants is in the range of 4 to 8 Kilometers below thesurface of the Earth, providing fluid temperatures of 100° C. to 200° C.

In the inventions to be described, hydrogen gas, derived from renewablesources such as wind power generators (or, as it is further developed,solar energy generators) is stored and then used in several ways. Oneuse is as a fuel for hydrogen-fired boilers to produce hot, dry steam.Burning hydrogen to heat the boilers uses no carbon based fuels and thusmay operate as a closed loop system. In such a system there are zerocarbon emissions into the atmosphere and, in certain locations, zeroemission of the Criteria Air Pollutants recognized in the Clean Air Act.Another use of hydrogen is for injection in controlled amounts andtemperature into the working fluid to boost the heat energy content ofthe working fluids or to regulate the density of the steam or gasturbine working fluid. Regulating the density of the steam entering theturbine enables matching the turbine output to the load and heat contentof the working fluid is yet another use.

Moreover, the conversion of wind or solar (or other renewables) energyto electricity may then be used to decompose water into its constituentshydrogen and oxygen in an electrolysis plant or electrolyzer, whereuponthe separated gases may then be stored in tanks for later uses. Thus,hydrogen may be used as a storage media for electricity generated fromrenewable sources, a principle feature of the present invention. Thestored hydrogen is very useful as a fuel for heating water in a boiler,for modifying the energy density of working fluids, for neutralizing thepH of substances recovered from the geothermal fluids, including theworking fluids, or for neutralizing the pH of working fluids injectedback into the earth. Further, the storage of hydrogen provides thecapacity to respond to variations in both the demand for electricity andin the supplies of the renewable energy sources.

A further principle feature of the system is that the temperature of theworking fluid input to the turbines is carefully balanced usingspecially constructed heat balancers that utilize heat from the boilersfueled by the stored hydrogen gas to supplement and regulate the heatcontent of the working fluid at the turbine inlets. The system alsoincludes apparatus for separating various materials not chemically boundfrom the working fluids for reuse with a minimal expenditure of energyand zero emissions. Moreover, the system adjusts for variations in bothgenerator loading and energy source outputs. For example, wind powerelectric generation is subject to wide variations in output due toclimate conditions, time of day, etc. Conversion of the wind generatedelectricity to a storable form of energy (such as the stored hydrogen)that can be tapped on demand is provided by the present inventions aswill be described.

The Uses of Hydrogen

One source of hydrogen is to use the electric power generated byrenewable wind-powered turbines as shown in FIG. 1 to generateelectricity for use in an electrolysis process to produce hydrogen gas(See FIG. 3). The hydrogen thus produced may be readily stored for lateruse as needed. This provides a clean method of storing the energyderived from wind power for later use and for producing hydrogen gas foruse in the geothermal turbine generator system. The oxygen produced inthe electrolysis unit may also be stored for reuse or sold on thecommercial market. The design of the geothermal turbine system mayinclude compressing and burning the hydrogen gas output in a mainturbine stack to produce electricity during peak demand. The waste heatrecovered from the turbine operation may then be directed back tooperate both the Rankine Cycle process and the initial geothermal systemwithout requiring additional heat output from the hydrogen boiler. Theseuses of hydrogen thus make possible efficient increases of generatingcapacity in response to increased demand.

The primary use of hydrogen in the present novel system is as fuel forfiring boilers to generate high temperature steam to feed through theheat exchanging structure in the heat balancers so that the temperaturesof the working fluids driving the turbines may be regulated at peakefficiency. Hydrogen may also be injected into the source fluid inlet ofa heat balancer to augment and regulate the heat content of the sourcefluid. Further, a relatively small amount of the hydrogen may also beused to regulate the density of the working fluid fed to the turbineinlets. The injection of hydrogen gas into the working fluid inlet tothe turbines enables regulation—i.e., optimization—of the density of theworking fluid to provide the most efficient operation of the turbinegenerator in response to variations in demand. That is, the torqueoutput of the turbines can be closely controlled, by regulating thedensity of the driving fluid input to the turbine, to thereby regulatethe electricity output of the generator.

The hydrogen may be provided by electrolysis in an electrolyzer orelectrolysis plant powered by the wind power generators and stored foruse by the hydrogen-fueled boilers that are used to produce the steamfed to the heat balancers, which provide the optimum temperature workingfluid to the turbines. Thus, a zero emission, renewable source of energyis stored and utilized in these two methods of increasing the efficiencyof the steam driven turbine generators. The system is operated by acontrol system under software control that responds to inputs fromtransducers located throughout the system that sense temperatures,pressures, load variations, etc. to regulate the operation of the heatbalancing and hydrogen injection apparatus placed in the working fluidinlet paths to the steam driven turbines.

The apparatus for injecting hot hydrogen gas into the working fluid—thehydrogen injection unit—is preferably a cylindrical tube having at leasttwo manifolds attached to diametrically opposite sides of the cylinderand disposed along the full length of the cylinder. As will beexplained, the hydrogen injection apparatus may, for example, be used intwo different locations or applications in the system of the presentinvention. In one application, the cylinder may be placed on the inletside of a heat balancer. In another application, the cylinder conveysthe regulated working fluid from the heat balancer to the inlet of theturbine. In each application, both manifolds contain a large number ofmicro-capillary tubes or passages that are distributed over the surfaceof the cylinder within the boundaries of the manifold. Thesemicro-capillary tubes permit the entry of the hot hydrogen gas underpressure into the interior of the cylinder to mix with the workingfluid, thus reducing its density according to preset parameters underthe control of the control system.

The control of the amount of hot hydrogen admitted to the injection unitmay be provided by rare earth magnetostrictive (REM) valves. REM valvesoperate similarly to piezoelectric devices, but respond to magneticfield variations used as control signals instead of electric fieldvariations. As in the heat balancer to be described, the surfaces of theinjection unit are preferably coated with a boron nitride or carbonnitride ceramic coating. The same basic injection unit design may beused elsewhere in the system, such as at the output of the cavitationseparator (to be described) for the injection of selected gases toprovide an operational enhancement. When used to control the hydrogeninjection, the REM valves themselves may be cooled using thermoelectriccoolers as also described below for the cavitation separator.

Hydrogen injection may be used for yet another purpose in the presentinvention: to adjust the pH of the working fluid. This has severalbenefits: (a) to facilitate cleaning because of the more neutral pH ofthe working fluids; and (b) to enable precipitation of certain mineralsfrom the working fluids during electrolysis. Such metals and mineralbearing elements as copper, silver, uranium and other radioactivematerials, chromium, vanadium, cobalt, phosphorus, sulfur, magnesium,potassium, sodium, and chlorine (to name a few) may thus be recoveredfor other uses.

The Renewable Energy Power Plant

The renewable energy power plant according to the present invention willbe described with the aid of FIGS. 3, 4, and 5. These figures arecomposed to demonstrate basic principles of the inventions and how theymay be utilized. FIG. 3 illustrates a simplified renewable power plantsystem. FIGS. 4 and 5 illustrate certain aspects of the system directedto several exemplary embodiments. The boldface capital letters A and Bthat appear in FIGS. 3, 4, and 5 serve as reference points in common aswill be described. Persons skilled in the art will recognize that manyvariations or combinations are possible by consideration of thealternatives shown in FIGS. 3, 4, and 5 when reviewed together. In thenext few paragraphs, some general descriptive comments will be presentedas an aid to understanding this relatively complex system, before thestructural details are described.

A simplified drawing of a renewable energy power plant system (REPPS)according to the present invention is shown in FIG. 3. FIG. 3illustrates one embodiment of a basic system to demonstrate how variouselements or components may be used together to enhance efficiency andoptimally balance available renewable energy resources to produceelectricity that matches the demand for electricity at any particulartime. As will be recognized by persons skilled in the electricgenerating system arts, many combinations of these components arepossible, including combinations that require one of more of thestructures shown in FIG. 3 in multiple places in the system. However,the embodiment illustrated in FIG. 3 includes the structural featuresneeded to demonstrate the principles of the present invention, whichutilizes renewable energy sources in a novel way that may be applied ina variety of ways without departing from the scope of the invention.

In general, the system illustrated utilizes geothermal energy and windenergy sources. Both sources are considered to be renewable, and are notsubject in practical terms to depletion. Each renewable source isprocessed separately in respective branches. The respective outputs froma geothermal (first) branch and a wind energy (second) branch are mergedin a heat balancing apparatus and process to provide hot, dry steamoptimized to drive a steam turbine electric generator at maximumefficiency. Although FIG. 3 appears complex, it may be readilyunderstood by recognizing that there are three basic circuits in thesystem.

The first basic circuit in FIG. 3, called the “primary source side,”processes the geothermal fluid pumped from the hot rock strata deep inthe Earth's mantle. This circuit is located in the lower center andright corner of the drawing and corresponds to the first (geothermal)branch. The second basic circuit, called the “demand side,” contains thecircuits and apparatus for processing the working fluid. The workingfluid receives its initial heat energy from the geothermal fluid. Theheat energy content of the working fluid is further boosted in the heatbalancers to suitable levels for driving the turbines at maximumefficiency. The demand side is located in the upper half of the drawingand may be thought of as corresponding to the output section of thepower plant. The third basic circuit, called the “secondary source side”in this description, is located along the left side of the drawing. Thesecondary source side contains the circuits and apparatus for producingand processing hydrogen gas that will be used in the system to enhanceits efficiency. The secondary source side receives energy originatingfrom wind power generation and thus corresponds to the second (windenergy) branch mentioned herein above.

In the first branch of the basic system of FIG. 3, the “primary sourceside” corresponding to the first basic circuit, geothermal fluid pumpedfrom a production well deep into the Earth's mantle may be circulatedthrough a phase separator (to be described) and input to a heatexchanger (the “geothermal heat exchanger”) to transfer the heat contentof the geothermal fluid to a working fluid. The heated working fluid mayreceive a metered amount of hydrogen as described above to optimize itsenergy content. Thus fortified, the heated working fluid is available tofeed to an input of the demand side of the heat balancer. Upon exitingfrom the geothermal heat exchanger, the cooled geothermal fluid, havinggiven up much of its heat energy to the working fluid, may be routed toan injection pump to return it to an injection well, less that portionof its heat energy that was transferred to the working fluid to drivethe turbine.

In the second branch, the “secondary source side” corresponding to thethird basic circuit, wind-generated electricity is routed to anelectrolysis plant similar to the one illustrated in FIG. 3. Theelectrolysis plant utilizes the wind generated electricity to decomposewater into its constituent elements, oxygen (O₂) and hydrogen (H₂). Eachof these gases is then stored in tanks until needed for use in thesystem or transported for other uses. The tanks may be especiallydesigned, above-ground storage tanks or, for large volumes of gas,underground abandoned salt caverns may be used. In the present system ofFIG. 3, the hydrogen may be piped to a hydrogen-fired boiler to heatwater for producing hot steam to be used in the “demand side” of thesystem. The steam is then available to feed to an input to the sourceside of a heat balancer as will be described in detail herein below.

In an alternate embodiment in regions where wind power generation is notavailable, but sufficient sunshine is available, the solar energy may beconverted to hot water and/or steam. This embodiment, though notillustrated herein employs well-known technology such as an array ofheliostats focused on a water or fluid-bearing pipe as a target. Ageneral description of the use of heliostats, including a simplifiedsystem diagram (See FIG. 3 in the article), is contained in an articleentitled Concentrating Solar Power: Energy from Mirrors, by L. Poole,DOE/GO-102001-1147, PS 128, March 2001, produced for the U.S. Departmentof Energy by the National Renewable Energy Laboratory, and incorporatedherein by reference in its entirety. The article is available atwww.nrel.gov/docs/fy01osti/28751.pdf. Thus, solar energy may be used toheat water or other suitable fluid to very high temperatures for use ina heat balancer. The steam thus produced may be used as a source fluidfed to the heat balancers. Solar heating may also be used to generateelectricity for use by the electrolysis facility to produce the hydrogenneeded for injection.

In the heat balancer, heat from the hot steam source is transferred tothe working fluid flowing in the demand side, leading eventually to theinlet to a steam turbine that is coupled to and configured to drive anelectric generator. The output of the heat balancer, the working fluidon the demand side, may be enhanced by the injection of a small amountof hydrogen gas as a means of controlling the torque output of theturbine in response to the electricity load (“demand”) on the generator.The electricity generated by the turbine generator may typically berouted to a substation in a distribution grid or network (not shown).The hot steam source fluid, after passing through the turbine where muchof its heat energy content was given up to the working fluid, may berouted to a condensing section of the system (condensate tank 180) to bestored or recirculated as working fluid. In some embodiments, asillustrated in FIG. 3, the spent steam working fluid may be passedthrough a heat balancer to replenish some of the lost heat energy beforebeing routed to the geothermal heat exchanger.

Returning to the first, geothermal branch of the system shown in FIG. 3,routing the extracted geothermal fluid through a phase separatorprovides for extracting various potentially useful constituent elementsfrom the geothermal fluid. There are at least two purposes for includingthis auxiliary capacity in the system. First, it removes constituentssuch as elements or compounds that are corrosive or abrasive that couldbe harmful to the components of the system. Removing these materialsextends the time between plant shut down for maintenance, cleaning, etc.A second reason for extracting these materials is that many of them havecommercial value, which justifies processes for separating and storingthem for later uses. In the system illustrated in FIG. 3, a cavitationphase separator is used to separate gases and some vapors from thegeothermal fluid. Precipitated solids may be routed to one storage areaor to a solution mining section of the system. Similarly, fluidmaterials may be stored or routed to the solution mining section.Finally, gases released during the cavitation process may likewise bestored for later use or routed to the solution mining section. Some ofthe separated constituents may be waste materials or harmful to theatmosphere if released. Thus, separate processing in a pollution trapmay be necessary to extracting and containing them within the system.

Continuing with FIG. 3, there is illustrated one embodiment of arenewable energy power plant 100 (alternately, “system 100”) accordingto the principles of the present invention. The principle components ofthe first circuit, the “primary source side” of the system 100 are ageothermal heat exchanger 102, a phase separator 104, and a pollutionprevention (“P2”) trap 106.

The principle components of the second circuit, the “demand side” of thesystem 100 are first 150 and second 152 heat balancers, a steam driventurbine 154, an electric generator 156, a hydrogen-fired boiler 158, anda control system 160.

The principle components of the third circuit, the “secondary sourceside” of the system 100 are an electrolysis plant 200, storage tanks202, 204 for hydrogen and oxygen respectively, and first 162 and second164 hydrogen injector units.

Referring to the first, or primary source side “circuit,” geothermalfluid such as dry steam or brine from deposit 60 is pumped through wellpipe 62 by pump 64 and through casing or conduit 66 to the inlet of thephase separator 104. Following removal of the gaseous materials from thegeothermal fluid in the phase separator 104, the geothermal fluidcontinues from the output of the phase separator 104 through conduit 112to the inlet of the geothermal heat exchanger 102. The geothermal heatexchanger 102 is structurally similar to the heat balancers 150, 152that will be described herein below in conjunction with FIGS. 6, 7, and8. The main difference between them is that the heat balancers 150, 152include an integral hydrogen injection unit and may be scaled upwarddimensionally to accommodate greater fluid volume and/or viscosity.

After giving up much of its heat energy in the geothermal heat exchanger102, the cooler geothermal fluid continues as the “geothermal return”through conduit 76 to be pumped into an injection well 72 by a pump 74,where the fluid is returned to a return deposit 70. Gaseous materialsare removed from the geothermal fluid by the phase separator 104, which,in the present invention operates according to a cavitation process, aswill be described for FIGS. 9-13. Briefly, the cavitation processvigorously agitates or shakes the geothermal fluid such that thepressure of the gas that is mixed within the fluid is allowed toincrease causing the gas to escape from the fluid and exit via a conduit114 to a pollution prevention (“P2”) trap 106. The pollution trap (P2)106, as will be described for FIG. 14, provides cooling sufficient tocondense the gaseous substances into their constituent liquid form andseparation into separate vessels (G1) 120, (G2) 124, (G3) 128, and (G4)132 via the respective coupling pipes 118, 122, 126, and 130. The use offour vessels, instead of some other number, is illustrative and notintended to be limiting; other numbers or even types of vessels orreceptacles are contemplated. Water remaining in the P2 trap 106 may bedrained via pipe 134 into a water storage tank 136. The water in tank136 may be pumped to the electrolysis plant via the conduit 138 forrecycling.

Turning now to the second, demand “circuit” of FIG. 3, the working fluid(which may be an organic substance) that absorbs heat from thegeothermal fluid in the geothermal heat exchanger 102 flows in a closedloop beginning with conduit 170 that passes through a “demand side” ofthe first heat balancer 150, then flows via conduit 172 through astand-alone hydrogen injector 164, thence through conduit 172 to theinlet of the steam turbine 154. Following expansion and a correspondingsteep pressure drop, during which the heat energy performs work on theturbine blades, the working fluid, now of diminished enthalpy, flowsthrough conduit 176 through the “demand” side of a second heat balancer152 to replenish its heat energy payload prior to being piped throughconduit 178 into a condensate tank 180. In condensate tank 180, thegaseous or vapor components of the working fluid are condensed forstorage or reuse, and the cleansed and replenished working fluid passesthrough a conduit 182 into the demand side of heat balancer 152 torepeat the process.

In operation, the recirculation of the working fluid for the steamturbine 154 is continuous, with heat energy replenished by the heatbalancers 150, 152. The heat energy for replenishing the working fluidis provided in the “source side” of the heat balancers 150, 152.Circulating in the source side of the heat balancers 150, 152 via therespective conduits 184, 188 (on the inlet side) and respective conduits186, 190 (on the return side) are intermediate working fluids—hot steamproduced by the hydrogen-fired boiler 158. The working fluid circulatingin the demand side of the heat balancers 150, 152 may further be subjectto modification in some systems by the respective stand alone hydrogeninjectors 162 and 164 along conduits 170 and 172. Hydrogen injector 162is provided to optimize the energy content of the working fluid bydecreasing its energy density. The hydrogen injector 164 is provided toregulate the density of the steam inlet to the generator 156 byinjecting a small amount of hydrogen directly into the steam path. Onlysmall amounts of hydrogen are needed to have a pronounced effect on thedensity of the steam entering the turbine 154. Through controlling thesteam density, the torque applied to the generator shaft may beoptimally matched to the load requirements. In cases where it is desiredto increase the density, oxygen (O₂) may be injected into the steamentering the turbine. The hydrogen injectors 162, 164 may be controlledeffectively by the use of rare earth magnetostrictive (REM) valves 206,208 respectively. REM valves 206, 208 operate similarly to piezoelectricdevices, but respond to magnetic field variations 8 used as controlsignals instead of electric field variations.

Turning now to the third secondary source side “circuit,” anelectrolysis plant 200 may be operated by electricity generated bywind-driven turbines (See FIG. 1) and applied to the electrodes withinthe electrolysis plant 200. Since the basic structure and operation ofan electrolysis system are well known, it will not be further describedherein except to say that when suitable positive and negativeelectrodes, immersed in water that is obtained, for example, from arainwater reservoir 198 as shown (or, alternately, water returned fromthe turbine cycles that has been cleaned), are connected to a source ofdirect current, the current causes dissociation of the hydrogen andoxygen atoms which are released into the atmosphere surrounding theelectrodes, where the gas molecules may be collected for storage. In thesystem illustrated in FIG. 3, the hydrogen and oxygen are respectivelydrawn into storage tanks 202, 204 through conduits 220, 222. In thepresent system, the hydrogen stored in tank 202 may be piped via conduit224 to the hydrogen injection units 206, 208 as controlled by the REMvalves 206, 208 respectively. the hydrogen gas from the storage tank 202may also be used as a fuel for operating the burner(s) (not shown inFIG. 3) to produce high temperature steam used to boost the temperatureof the working (organic) fluid that is fed to the inlet of the steamturbine.

The Control System

One other feature of FIG. 3 illustrated therein is a control system 160in the upper right hand corner of the drawing. The control system 160may be implemented as a computer control system and method forcontrolling the heat balancing, hydrogen injection, and other systems ina renewable energy power plant to optimize the operating efficiency ofthe generating system and to balance the electricity outputs in responseto the demand for power.

Operating these various elements in a coordinated and efficient mannerrequires the use of a feedback control system, preferably one thatoperates according to program instructions executed by a computer. Ingeneral, the control system consists of (a) an input network of sensorsdeployed in various parts of the system; (b) a control logic sectionsuch as a system of electronic feedback circuits or one or moreprogrammed computers that receive and operate on the input signals fromthe sensors; and (c) an output network of valves, actuators, or othercontrol devices operated by the control logic and deployed at variousother parts of the system for adjusting operating parameters of thesystem in response to operating conditions measured by the sensors andprogram sequences executed by the computer(s). The sensors and controlelements are typically transducers especially configured for aparticular task. Remote terminal units (RTUs) and programmable logiccontrollers (PLCs) are typically located at various locations or nodesof the system to interface with the sensors and control elements underthe control of a distributed control system (DCS) and/or a supervisorycontrol and data acquisition (SCADA) system. A human-machine interface(HMI) may be coupled to the SCADA or the DCS to enable supervisoryinteraction with the system. All of these units and controllers are wellknown devices that operate according to known communication andoperational protocols in the industries involved in electric powergeneration and distribution.

In the feedback control system of the present invention, for example,sensors coupled to RTUs or PLCs may be used to measure such parametersas the temperatures, pressures, flow rates, and densities of the workingfluids and gases, particularly the density, temperature, and volume ofthe hydrogen gas at various points in the system. Control devices suchas motors, actuators, and valves, under the control of other RTUs orPLCs, adjust the flow of the working fluids, or the mixing of fluids ofdifferent temperatures, to maintain the fluids at optimum temperatures.One example of a control element is a rare earth magnetostrictive (REM)valve that is used as explained above to adjust the amount of hydrogeninjection into the working fluid of the steam turbines. The controllogic section, such as may be incorporated in the DCS, whichinterconnects the RTUs and PLCs, contains and executes the operatingprograms for configuring the system at a desired output and foradjusting the operating parameters of the system in response toconditions of renewable energy supply (climate, geothermal parameters,etc.) and electricity demand (loading of the grid, time of day, etc.),while maintaining operating efficiencies within a prescribed range. Thiscontrol mechanism is preferably performed in real time to maintainoptimum efficiency. With appropriate pre-set limits, decisions can bemade and the system ramped up or down as needed to adjust to changes ineither the supply side or the demand side, or both. A SCADA system,which may be generally located in a central office building at eachrenewable energy power plant system, may be coupled to the DCS foracquiring and monitoring the data provided by the sensors, adjusting setpoints for control, and the like. The various units of the system arecoupled together via communications links or networks. Major functionaltasks of the control system include: (a) that it must be integrated intothe power distribution grid; (b) coordinating power delivery with theload requirements including power factor, etc.; (c) tracking the variousparameters and BTU values in real time throughout the system; (d)providing appropriate responsive control and adjustment to operatingconditions; and the like.

Thus, in one embodiment of a renewable energy power plant theprogrammable control system 730 may include, as in the example shown inFIG. 15, a first network of input sensors S₁, S₂, S₃, . . . Sx (732,734, 736 . . . 738) coupled to a programmable computing system 740 anddisposed at first selected locations in the system for monitoringoperating parameters; a second network of control devices Ca, Cb, Cc, .. . Cy (742, 744, 746, . . . 748) coupled to the computing system 740and disposed at second selected locations in the system for controllingthe operating parameters; an executable program set 750 providinginstructions to the programmable computer system 740 coupled to thefirst and second networks to receive input signals from the firstnetwork and to send commands to the second network for executing controlactions in the second network in real time according to (a) theexecutable program set 750, (b) status data regarding the supply ofrenewable energy 752 and the demand for electricity 754, and (c) a rangeof user preset operating points for maintaining an operating balancethat optimizes efficiency.

Continuing with FIG. 15, the first network includes the sensors 732 . .. 738 and the programmable computing system 740. The second networkincludes the control devices 742 . . . 748 and the programmablecomputing system 740. The coupling of the sensors and control devices tothe programmable computing system may be via any suitable communicationslink including wired, wireless, optical fiber, conveying base band ormodulated data, etc. The programmable computing system 740 may include aserver system and/or a network of PLCs. The executable program set 750may include an operating system, a portfolio of application programs,and a plurality of PLC function charts or ladder diagrams configured forcontrolling and operating a renewable energy power plant. Theprogrammable computing system 740 may include various user interfacesfor monitoring and control, entering presets, running diagnosticprograms, and the like. The implementation of a specific design for aspecific system is readily within the level of skill in the art and neednot be elaborated further herein.

Referring to FIG. 4, there is illustrated a flow chart diagram of oneaspect of the embodiment of FIG. 3. FIG. 4 illustrates the aspect of therenewable energy power plant according to the present invention thatemphasizes the merging of two renewable energy processes represented bytwo different energy input branches. The two energy input branchesinclude a wind/solar energy branch and a geothermal branch. Energy fromthese two branches is processed and merged in a heat balancer apparatus,which may include an integral hydrogen injection unit. The heat balancerprovides high temperature working fluid, of a density optimized for theloading present on the distribution grid, to drive the steam turbinegenerators at maximum system efficiency to produce the desiredelectricity output. In the wind/solar branch, corresponding to step 240,the process begins with the generation of electricity by operation ofwind generators (See FIG. 1) or, alternatively, through the use of suchwell-known solar powered converters as a heliostat array for heatingwater or other fluids to high temperature steam for driving a turbinegenerator, a bank of photovoltaic converters for generating electricity,etc., in step 242. The electricity thus produced is conducted to anelectrolysis plant to produce hydrogen and oxygen for storage inseparate tank facilities, in step 244. In this way, the electricityproduced from the renewable but variable wind (or solar) generators maybe stored in the form of hydrogen or oxygen gas for later use. Suchstorage enables normalizing the wind-generated output (or thesolar-generated electricity) to more uniform, predictable levels. Suchstorage of hydrogen further enables the availability of a carbon-freefuel for providing heat, in the form of high temperature (hot) steam,for providing the energy to ultimately drive turbines coupled toelectric generators. For example, in step 246, hydrogen-fired boilers(158 in FIG. 3) may be used to heat water, converting it to the hightemperature steam, which may then be conducted to the heat balancer(process step 260 in FIG. 4) in step 248. Thus, the wind (or solar)energy branch 240 provides the source fluid—and the high temperaturesteam—to boost the temperature of the working fluid on the demand sideof the system, which drives the turbine generators 156. The use ofhydrogen as a fuel obviates the need for pollution controls or othermeasures to limit the release of combustion by-products fromcarbon-based fuels into the environment.

Considering now the second branch of the system, in the geothermalbranch 250, the process begins with the extraction of geothermal fluidfrom beneath the surface of the Earth in step 252. Upon extraction fromthe production well 62 by pump 64 (See FIG. 3) the geothermal fluid isrouted through a phase separator 104 to undergo a phase separationprocess in step 254. Step 254 separates gases from the geothermal fluidbefore transferring the heat energy in the geothermal fluid to theworking fluid in step 256 in the geothermal heat exchanger 102. Theworking fluid, with its elevated heat content, is then conducted in step258 to a source side inlet of a heat balancer 150 at block 260. In theheat balancer 150, in the process that takes place in block 260, theworking fluid absorbs additional heat from the hot steam produced in thehydrogen-fired boiler 158 during the steps 246 and 248 described hereinabove.

Returning to step 256, the geothermal fluid, after yielding its heat tothe demand side working fluid in the geothermal heat exchanger, in step280 is circulated through conduit 114 to be pumped into an injectionwell. It should be noted that both process paths that follow step 256are identified with the boldface capital letters A and B. These lettersidentify reference points that are also shown in FIG. 3, which are theconduit 170 leading to a heat balancer input (Ref. A) and the conduit114 leading to the injection well 72 (Ref. B). These reference pointsare so identified because they are convenient power plant expansionbusses—common points in the energy-bearing conduits where additionalstructural sections may be added, essentially in parallel, to expand thecapacity of the power plant to meet varying demands for electricity,from base load levels to peak load levels. An example of this expansionin capacity is illustrated in FIG. 5, which shows how multiplegenerators may be combined to provide increased capacity. The referencepoints A and B shown in FIG. 5 show the location of the connectionpoints for the additional generator branches, using the same basic plantarchitecture described for FIG. 3 and the process diagram of FIG. 4.

As described herein above, the process performed in step 260 in thespecially configured heat balancer 150 causes the working fluid, whichis typically pre-heated in the geothermal heat exchanger 102, to absorbconsiderable additional heat energy from a source side input of very hotsteam produced by the hydrogen-fired boiler 158. The temperatures andthe amount of heat added, as well as a number of other parameters to bedescribed, are regulated quantities controlled by the control system160. The process step 260 may also include the injection of hydrogen gasinto the source side fluid to optimize its density and heat energy levelfor the generating load presented to the renewable energy power plant.step 256. From the heat balancing process 260 the working fluid isconducted to the input of the turbine 154 in step 262. The working fluidmay further receive a small amount of hydrogen gas injection in step 264to trim the density of the steam fed into the turbine in order to matchthe torque produced by the turbine 154 to the electricity demand uponthe generator 156. In step 266, the steam drives the turbine, which iscoupled to the electric generator The output of the generator 156 iscoupled to the electric grid in step 268, thus providing the electricityoutput 270 to meet the demand therefore.

Continuing with FIG. 4, and returning to process step 260, the hot steamresidue, after passing through the sources side of the heat balancer150, is directed to a condensation step 282. The flow then advances tostep 284 to precipitate solid matter from the condensed solution if sucha step is needed. Solid matter thus separated out of solution may thenbe stored in step 286 for later processing or reuse. After theprecipitation step, a decision step 288 is performed to determinewhether the solution—i.e., condensed steam—is to be recirculated orpumped to a reservoir or storage area. If the condensed steam is to berecirculated, the process returns to the entry to step 256. However, ifthe decision is to store the condensed steam, the flow advances to step290 to pump the water to a reservoir for storage. It will be noted thatthe processes of FIG. 4 operate continuously as long as the power plantis operating.

Referring to FIG. 5, there is shown a block diagram of another aspect ofthe embodiment of FIG. 3. FIG. 5 illustrates a portion 300 of arenewable power plant architecture, which includes multiple heatbalancer and turbine-generator combinations. In FIG. 5, as well as inFIGS. 3 and 4, the connection points for the additional heatbalancer/generator combinations, identified by the capital letters A andB, are shown to enable cross referencing the three figures. Point Arepresents a steam bus 370 for conveying high temperature steam from thehydrogen boiler 350 (similar to the hydrogen-fired boiler 158 in FIG. 3)to the respective inputs to the heat balancers 332, 334, 336, and 338.The input to each heat balancer includes a hydrogen injection section,respectively 342, 344, 346, and 348. The high temperature steam isadmitted to the respective inputs to the hydrogen injection units input,respectively 356, 358, 360, and 354. The steam exiting from the heattransfer sections of the heat balancers is conveyed to a return bus 372for return to the hydrogen (H2) boiler 350 to be reheated.

Continuing with FIG. 5, the outputs of the heat balancers 332, 334, and336 are coupled to the inlets 316, 318, and 320 of the turbinegenerators 301, 304, and 307. The respective turbines 302, 305, and 308in each turbine generator drive a corresponding electric generator 303,306, and 309 to produce electricity to be delivered to a distributiongrid at respective outputs 310, 312, and The turbine generatorcombinations may be sized to accommodate varying electricity loads. Forexample, the turbine generator combinations 301, 304, and 307 may besized to produce, respectively, outputs of 0 to 125 MegaWatts (MW), 0 to10 MegaWatts (MW), and 6 to 20 MegaWatts (MW). Through system control,the outputs may be adjusted to match the electricity supply to the loadconditions, ranging from base load to peak load.

The steam that exhausts from the turbines, which has a much lower energycontent, may be directed to other system locations as follows. In oneexample, the exhaust from turbine 302 may be conducted back to point A(352) to mix with the working fluid input to the input 356 of thehydrogen injection section of the heat balancer 332 for reuse in thesame turbine generator 301. The heat lost in the turbine 302 is replacedduring this recycling process by heat transferred from the hot steamproduced by the hydrogen-fired boiler 350. In a second example, theexhaust steam from turbine 305 may be conducted to a water/gascondensate tank 380. From the tank 380, the condensed fluid may beconducted through conduit 384 to be mixed with other exhausted workingfluids at point B (362) and injected along conduit 322 into the Earth atan injection well 72 (See FIG. 3). Another use for a water/gascondensate tank 380 is to collect such gases as CO₂, H₂, H₂S, and otherbyproducts produced in the power plant and condensed for re-use. In athird example, the exhaust from the turbine 308 is shown coupled to theinput 354 of a fourth heat balancer 338 that is provided for processingsuch waste steam by increasing its heat energy to correspond with theheat energy content of the geothermal fluid obtained from the productionwell. Such processing enables replenishing the geothermal resource whenit is not needed for the operation of the power plant. It is an exampleof the closed loop architecture of the present invention that minimizesthe release of waste materials into the atmosphere. These examples areintended to be illustrative of some of the possibilities in a renewableenergy power plant as described herein and not limiting.

The Heat Balancer

In the present invention, a heat balancer, placed at selected positionspreceding the working fluid inputs to the turbines, is used to add heatenergy to the working fluid as needed and to regulate the temperature ofthe working fluid. The heat balancer transfers heat from hightemperature steam provided by hydrogen-fired boilers to the geothermalfluid from the production wells. This enables the system to augment andregulate the heat content of the geothermal fluid to compensate fornatural variations, thus realizing a substantial boost in the operatingefficiency of the turbines. Another component of the heat balancersprovides for injection of hydrogen or other combustible gas into thegeothermal fluid entering the heat balancer to supplement the energydensity of the geothermal fluid. As will be described herein below, inanother application of the injection function, combustible gasessuperheated by hydrogen may be injected in small amounts into thethermally enhanced working fluid just prior to the inlet of the turbine.Increasing the energy density in this way at this location enablesregulation of the torque produced by the turbine, thereby controllingthe electrical output of the generator driven by the turbine.

The heat balancer includes a specially constructed, counterflow-typeheat transfer mechanism that operates in a feedback control loop toregulate its operation using the control system to be described. Theheat balancer to be described includes several additional features notfound in a conventional heat exchanger. In a typical heat exchanger, onecommon function is to dissipate excess heat from a working fluid flowingin a closed circuit to a cooler external environment such as the air ora large body of water. In such heat exchangers the flow of the singlefluid often proceeds along a loop-back path. In some heat exchangers ofhigher efficiency employing a flat plate, counterflow construction,which transfer heat from one fluid to another, the flow of the hotterfluid and the flow of the less hot fluid are in opposite directionsrelative to each other, i.e., in “counterflow.” Some embodiments of theflat plate heat exchanger construction may include embossed patterns inthe plates.

Several aspects of the heat balancer to be described employ acombination of features that differentiate it from ordinary prior artheat exchangers. First, the heat balancer described herein adds heatfrom one fluid flowing in a closed circuit (hotter side) to a workingfluid flowing in another circuit (cooler side), which is enclosed withinthe heat balancer. Second, the flow of both the source and demand sidefluids in the heat balancer described herein is direct, that is, in onedirection from its inlet port to its outlet port. Third, in the heatbalancer of the present invention the source side and the demand sidepassages are separated by flat plates such that the source side anddemand side passages alternate because of the interleaved internalstructure of the passages in the heat balancer. Fourth, each of theplates includes a particular herringbone pattern formed into the platesto increase their surface area and promote a predetermined amount ofturbulence. Fifth, the heat balancer described herein includes a devicefor injecting a supplementary compound or element, such as hydrogen gasor other substance into the inlet or outlet of either side (source ordemand) of the heat balancer. Preferably, in the embodiments describedherein, the heat balancer includes an injection unit installed in thedemand side inlet to inject, for example, a combustible gas such ashydrogen to modify the energy content or density of the demand orworking fluid. Sixth, the internal surfaces of the heat balancer incontact with the fluids may be coated with very hard,corrosion-resistant materials such as born nitride (BN) or carbonnitride (C₃N₄).

In the heat balancer described herein, the heat transfer mechanismincludes a source fluid (hotter) side and a demand fluid (less hot)side. The source fluid side admits the high temperature steam that isobtained in this example from a hydrogen boiler. The demand fluid sideadmits the lower temperature working fluid from the geothermalproduction well that is routed to an inlet to the turbine after its heatenergy is increased. These two sides are separated in the heat transfersection of the heat balancer by an enclosed structure formed of an arrayof thin, substantially flat, parallel plates having herringbone-patternsurfaces for maximum surface area and heat transfer. The source anddemand fluid passages are interleaved and may be enclosed in a box-likehousing. The housing may be configured in other forms, such ascylindrical or other shape that facilitates the flow of fluids withinit. Thus, a first (source) working fluid circulates through one set ofpassages between alternate pairs of plates, while the second (demand)working fluid circulates through another set of passages disposed—i.e.,interleaved—between the remaining pairs of plates. The flow of the twoworking fluids is in opposite directions on either side of each plate,that is, in counterflow with each other, in order to obtain maximum heattransfer from one fluid to the other. The thin plates may be fabricatedof stainless steel, vanadium steel, molybdenum steel, and the like. Aherringbone pattern may be formed into the plates to enhance thetransfer of heat without impeding the flow along the surfaces of theplates. The herringbone surfaces are coated with a material imperviousto corrosive effects or chemical attack from the working fluid andpossess a very high heat transfer rates. Suitable materials for thiscoating include ceramic nitrides of boron, carbon, etc.

In operation, very high temperature steam produced in a hydrogen-fueledboiler is pumped through a source side inlet to the heat balancer. Theworking fluid enters a demand side inlet of the heat balancer and flowsthrough it to absorb heat energy transferred from the hot steam flowingin the source side, then exits from an outlet manifold toward the inletto the turbine with its elevated heat content. The two working fluids donot mix because their respective sets of interleaved passages areseparated by the flat plate structure. The temperature of the thermallyenhanced working fluid may be controlled within a one degree toleranceto match the optimum operating temperature of the turbine. The workingfluid, after circulating through the turbine, exits toward a condensatetank to be available and balanced for reuse.

Heat balancers may also be located at the production wellhead toregulate the temperature of the geothermal fluids from the productionwell. A third location for a heat balancer is at the exit point of thesystem, to regulate the temperature of the geothermal fluid returned tothe rock strata beneath the earth's surface. This combination ofcomponents enables not only high efficiency electricity generation fromrenewable sources but it also operates as both a base load system and apeak load system, depending on the demand for electricity.

Additionally, the geothermal system of the present invention iswell-suited as a back-up power source for wind power generation that isexperiencing low output due to reductions in the prevailing winds thatoccur from time to time. This is in contrast to conventional geothermalsystems, which are capable of operating as base load systems only.Moreover, the flow of heat to the heat balancers makes this system'sflow diagram completely reversible to allow heat flow input as well ascontrol of hydrogen injection points such that the system becomes astand alone power plant for generating electric power. The heatbalancers may also use a variety of heat sources including directapplication of solar heating to a heat balancer, or solar thermal fluidsmay be used in conjunction with hydrogen generated from wind or solargenerated electricity.

In one example of a stand-alone power plant, the system of FIG. 3 minusthe components connected to the inlet side of the geothermal heatexchanger 102, which include the geothermal fluid, the cavitation phaseseparator, and pollution prevention trap, etc., may be used as anadjunct to a wind power generation facility that lacks access togeothermal fluids of a suitable temperature. Thus, the hydrogen-basedgeneration capability may be used to optimally supplement the wind poweroutput.

Referring to FIG. 6, there is illustrated a simplified plan view (fromabove) of a heat balancer apparatus of the embodiment of FIG. 3including a hydrogen injection manifold coupled thereto. This figure issimplified to illustrate the concepts embodied in the heat balancer.FIG. 6 shows the paths of flow of geothermal working fluid (demandcircuit) indicated by the solid arrows, and the high-temperature (sourcecircuit) fluid indicated by the open-bodied arrows through the heatbalancer. In this example of the structure of a heat balancer, it shouldbe noticed that the source side fluid flow (open arrows) is constrainedwithin a closed set or bank of parallel passages as viewed from above,wherein the spacing between the source fluid passage sides is uniformlymaintained at one unit value, indicated by the lower case letter m.Further, each pair of source side passages is spaced approximately threeunit values apart in this example, as indicated by the lower case letterk. The entire bank of source side passages is then seen to be nestedwithin an enclosure dimensioned to provide the narrower source sidepassages interleaved among the wider demand side passages. Thus, thewidth k of the demand side passages is approximately three times thewidth m of the source side passages. The unit value, m, in this examplemay be approximately one inch or 25.4 mm. The value k, in this example,may be approximately three inches or 76.2 mm. The actual values willdepend on the application.

Stated another way, the ratio of k/m=3. This is an intentional designfeature that provides an efficient balance of the flow volumes of thesource and demand fluids as well as allow for the greater proportion ofsolids suspended in solution that is likely with the demand side(geothermal) fluids. The structure illustrated in FIG. 6 also shows thatthe manifolds for the conveying of the fluids into and out of the heatbalancer are simple flow passages, being integrated into the design ofthe heat balancer. For example, the manifolds 427, 428 for the sourcefluid passages are shown joining the ends of the passages containing theopen arrows, and the manifolds for the demand fluid passages areprovided by the relationship of the outer shell (or first enclosure) 402and the source fluid bank 422 illustrated in FIG. 6. In one embodimentof the manifolds 427, 428, the surface of the manifolds 427, 428 incontact with the demand side (geothermal) fluid—i.e., the “external”surface—may preferably be configured with fins to enlarge their surfacearea and thus increase the transfer of heat from the source side fluid(hot, dry steam) into the demand side fluid. The flow of the respectivefluids is indicated by the arrows, with the relative temperature of thefluid at each arrow location indicated by the width of the arrow shaft.A narrow arrow indicates a lower temperature and a wider arrow indicatesa higher temperature. Thus, the demand side fluid gains heat and thesource side fluid loses heat as the respective fluids traverse the heatbalancer and the transfer of heat takes place from the source side (openarrows) to the demand side (solid arrows). The demand side fluid mayalso be thought of as the fluid that flows in the load side of the powerplant.

Continuing with FIG. 6, a heat balancer 400 is formed by a rectangularouter shell 402 (or first enclosure 402) enclosing a space there within.The enclosed space within the shell 402 provides for the flow of thedemand side fluid between an inlet 404 at a relatively low temperature454 and an outlet 406 at a relatively higher temperature 456. The flowfollows the solid arrows through the passages having a uniform spacing“k” and exits at an increased temperature 456 at the outlet 406 afterabsorbing heat energy from the source fluid. Disposed between the inlet404 and the shell 402 is a second enclosure 408. The second enclosure408 provides a chamber for injecting a combustible gas such as hydrogenor other substance via an injection port 410 into the incoming stream ofthe demand fluid, which will be described in detail for FIG. 7.

Continuing with FIG. 6, centered within the first enclosure 402 is astructure for containing and conveying the flow of source fluid throughthe heat balancer 400. This structure, briefly described herein above iscalled in this description a source fluid bank 422. The source fluidbank includes an inlet 424 and an outlet 426. Source fluid at arelatively high temperature 450 enters at the inlet 424, passes throughthe set of passages within the pairs of plates 430/432, 434/436,438/440, and 442/444 in this illustrative example. The flow follows theopen arrows through the passages having a uniform spacing dimension “m”and exits at a reduced temperature 452 at the outlet 426 aftertransferring most of its heat energy to the demand fluid flowing in thespace within the first enclosure 402. A careful review of FIGS. 6 and 7reveals that, while the shell 402 forms a housing for the heat balancer400, the combination of the shell 402 and the flat, parallel plates 430to 444 of the closed source fluid bank 422 that is enclosed within theshell 402 provides all of the structure necessary to direct therespective flows of the source side and demand side fluids in separate,interleaved passages and in opposite (counterflow) directions throughthe heat balancer 400.

Referring to FIG. 7, there is illustrated a side elevation view of theheat balancer apparatus of FIG. 6. Like FIG. 6, this figure is alsosimplified to illustrate the concepts embodied in the heat balancer. Theopen arrows flowing to the left represent the flow of the source sidefluid behind the plate 436. The solid arrows indicating the demand sidefluid are shown on the near side of a plate 436 of the source side bank(e.g., flowing to the right, in front of plate 436 in FIG. 6). It shouldbe apparent that, were this figure illustrating a heat balancer 400 inactual operation, the demand fluid indicated by the solid arrows wouldbe a unitary sheet of fluid extending from the top to the bottom of theheat balancer and flowing to the right in the figure in front of theplate 436. The demand side fluid 454 of low temperature is shownentering the inlet 402, passing through the injection chamber 408,thence into the demand side of the heat balancer at 464. Upon passingthrough the heat balancer, the demand side fluid flows at 462 toward theoutlet 406 and exits at a high temperature 456. Similarly, the sourcefluid enters inlet 424 at a high temperature 450, then enters the sourceside of the heat balancer at 466. The open arrows flowing to the leftrepresent the flow of the source side fluid behind the plate 436. Uponpassing through the heat balancer, the source side fluid flows at 460toward the outlet 426 and exits at a lower temperature 452.

Continuing with FIG. 7, the description of the gas injection manifold orchamber 408 will be provided. The gas injection chamber 408 includesspace for the demand fluid 454 to enter the inlet port 404. Theinjection chamber 408, which functions as a manifold for mixing anadditive substance such as a combustible gas into an incoming fluid, isshown as a double-walled structure having an outer shell 410 and aninner shell 412. A feed port 414 enables hydrogen or another injectionsubstance such as oxygen, for example, to enter the space between theouter 410 and inner 412 shells of the injection chamber 408 and mixedwith the incoming fluid. The inner shell 412 is equipped with a largenumber of orifices 416 that surround the enclosed space within theinjection chamber 408. In a preferred embodiment, the orifices 416 areprovided by microcapillaries for causing the hydrogen or other gas orinjected substance to diffuse into the injection chamber 408 as a veryfine cloud 418 of individual gas bubbles. The incoming demand fluid thenabsorbs—i.e., is mixed with—the bubbles of gas in a substantiallyuniform manner to provide the desired energy density.

The injection chamber 408 may alternatively be used as a stand-alonedevice or manifold positioned in-line in any conduit, pipe, or passagein which a fluid material bearing heat energy is flowing. Such aninjection chamber 408, equipped with an outlet port (not shown in FIG.7, but it would resemble the inlet port 404), enables injection of a gasinto the fluid to enhance or regulate its heat content, energy density,or provide an additive substance to promote cleaning of the interiorwalls of the conduits, etc. An example of an injection chamber 408 usedas a hydrogen injector is shown in FIG. 3, at reference numbers 162 and164.

Referring to FIG. 8A, there is illustrated a simplified diagram of thecross section of the heat balancer of FIGS. 6 and 7. In this view, whichcorresponds to the flow of source fluid toward the viewer, i.e., awayfrom the page, the narrower spacing m identifies the passage between theplates 430 and 432, which join the housing 402 at the ends of the plates430 and 432. The passage thus formed is wide (tall in this view) andnarrow (laterally in this view). The other spacings respectively between434 and 436; 438 and 440; and, 442 and 444 similarly represent the samefeature of the source fluid passages within the heat balancer 400,whereby the passages are formed primarily by wide, flat plates. It willalso be noted that the spacing k represent the separation of the pairsof wide, flat plates that form the source fluid passages.

Referring to FIG. 8B, there is illustrated a cross section view of aportion of one of the plates 430 of the heat balancer 400 of FIGS. 6 and7 that separate the source side and the demand side fluid flows. Theedge-wise view in FIG. 6 of the plates that form the large planar sideof the passages for the source and demand side fluids in the heatbalancer 400 indicate that the plates are flat planes. FIG. 8, however,by expanding (magnifying) the scale shows that the edge-wise view ofeach of the plates 430, 432, 434 . . . 444, indicates that the crosssection of the plates is a regular zig-zag or herringbone pattern havingan included angle of approximately 126 degrees and a peak-to-troughheight of approximately d=4 mm. This configuration of the platesprovides a consistent surface topography that has properties that affectthe flow of fluid and provide an impediment to scaling. Scaling is theaccumulation of deposits of substances such as calcium carbonate (CaCO₃)or gypsum (CaSO₄-2H₂O) from the geothermal fluids. In this example, theplates may be formed of ⅛ inch (3.2 mm) thick steel such as austeniticsteel—654 SMO and coated with a layer of boron nitride (BN) or carbonnitride (C₃N₄) to a thickness of 0.002 to 0.004 inch (0.05 to 0.10 mm)to resist corrosion and enhance heat transfer. Both of these coatingmaterials are characterized by excellent thermal conductivity and veryhigh hardness. The zig-zag form of the plates is a simple way toincrease the surface area of the plates, thereby increasing theirability to transfer heat from the hotter fluid to the colder one. Inthis example, given the angle and dimension in the previous sentence,the improvement by simple trigonometry is approximately 12%. Further,the plates may be oriented such that the direction of the zig-zag eitherruns the same direction or across the direction of the fluid flow. Flowwith the zig-zag tends to channel the flow of the fluids, increasing theflow rate; flow across the zig-zag produces more turbulence, andpotentially greater heat transfer but at the risk of increased depositsfrom fluid-borne impurities, called scaling, that remain in the fluidfollowing phase separation.

The Cavitation Phase Separator

The process of phase separation is well known in the oil and gas fieldas well as in the chemical industries, laboratories, etc. Phaseseparation, referring to the separation of mixtures of the chemicalelements found in nature into the three fundamental phases—solid,liquid, and gas, may be accomplished by a variety of processes. Theseinclude, for example, distillation, condensation, filtration,precipitation, electrolysis, and the like, which may be enhanced throughthe use of catalysts, the application of heating or cooling, or variousother mechanical or electrical processes, etc.

The renewable power plant system of the present invention illustrated inFIG. 3 includes a novel cavitation phase separator (CPS) for purifyingthe geothermal fluid prior to its use as a working fluid for driving thesteam turbines that provide the motive force for the generators. Thisgeothermal fluid, in addition to dry steam may include brine, gases,oil, solids in suspension, a variety of metals, minerals, etc.Cavitation is selected as a mechanism to provide the phase separationbecause of the efficiency inherent in resonant devices, and in therelative ease and economy with which it may be implemented. In theprocess, the geothermal fluid is fed into a container where it issubject to vigorous shaking forces produced by the walls of thecontainer. The shaking forces are sufficiently vigorous to inducecavitation in the fluid mixture, causing it to release low pressuregases and or vapors from the liquid mixture that are not chemicallybound together. The gases and vapors thus removed from the geothermalfluid may be gathered in storage tanks for further processing orcommercial sale to recover the economic value. Solid materials may beprecipitated out of solution, and the water vapor that is too cool foruse as a geothermal fluid may be condensed for storage or reuse.

The CPS is thus very useful as part of a system for efficientlyseparating out the constituent substances that are not needed fordriving the steam turbines. A CPS may also be used elsewhere in thesystem for purifying spent working fluids prior to reuse in the systemor replenishing the subsurface strata from which the geothermal fluidwas originally pumped. The cavitation phase separator described hereinproduces cavitation in the fluid material by agitating it using soundwaves generated by piezoelectric transducers. Cavitation occurs when thepressure of a fluid in motion drops below its vapor pressure. Thecavitation action vaporizes the fluid material such that the water vaporand gases boil off, are extracted, and transferred into storage tanksfor later use.

Two types of cavitation phase separators are described herein for use inthe system, both of which may be embodied in generally cylindricaltubes. In one illustrative embodiment, the cylindrical body or tube maybe about 2½ feet long and one foot in diameter, providing a resonantcavity within it. The geothermal fluids are pumped through pipes or flextubes attached to and aligned longitudinally along the outside surfaceof the cylindrical resonating chamber, en route to the heat balancers.These tubes are arrayed in contact with the outside of the cylindricalbody, surrounding the cylinder with their longitudinal axes parallel tothe axis of the resonating chamber. Contained within the cylinder is oneof two configurations of a piezoelectric transducer. As is well known inthe art, a piezoelectric material cut to a predetermined shape anddimension will expand and contract vigorously along one or more of itsdimensions or axes at its inherent resonant frequency when excited by analternating voltage of that resonant frequency. The amplitude of thevibration or displacement of the crystal is generally proportional tothe amplitude of the applied voltage. In one mode, called “3-1,” theaxis of vibration is generally perpendicular to the surface of thepiezoelectric crystal. In another mode, called a “3-3” mode, the axis ofvibration is generally along the surface of the piezoelectric crystal.This property is extremely useful in generating a controlled shakingforce to produce cavitation in the fluid material adjacent to the wallsof the piezoelectric resonator.

As noted herein above, agitation of the fluid substance due to thepiezoelectric action in the resonant chamber puts the fluid in motion.If the fluid is agitated vigorously enough at an appropriate frequency,the cavitation produces the vaporizing action that separates gaseousmaterials from the fluid. As a gross analogy, the process is somewhatakin to shaking a can of a carbonated beverage, which will enable theCO₂ mixed into the beverage recipe to escape.

One configuration of the phase separator, called a double-shellresonator, employs a linear piezoelectric stack that may operate in a3-1 resonant mode. This embodiment is illustrated in FIGS. 10 and 11.The cylindrical cavity for this configuration includes a pair of slotscut through the wall of the cavity (from outside to inside diameter)along two opposite sides of the cylinder, from end to end, forming twosemicircular shells whose concave sides face each other. The linearpiezoelectric stacks (in this example three such stacks may be used,each resembling a stack of dominoes) are each oriented along and acrossa diameter of the cavity and at right angles to the plane containing theslots. When the piezoelectric stacks are energized at resonance, the twosemicircular “sides” or shells of the cylinder, respectively attached tothe opposite ends of the stacks, vibrate toward and away from eachother, alternately compressing and expanding the volume of the cavity,and thus shake the contents of the fluid tubes attached to the outsideof the cavity shells. The cylinder may be suspended by acousticallyinsulating supports.

The second type of phase separator configuration, illustrated in FIGS.12 and 13, may be called in this context a single shell or tuning forkresonator in which the inside cylinder wall is lined with a thin-walledpiezoelectric cylinder and may operate in either a 3-1 or a 3-3 mode.The cylindrical cavity includes a single slot cut through the cavitywall and the piezoelectric lining from end-to-end, parallel to itslongitudinal axis, on one side of the cylinder only. Thus, in crosssection, the cavity somewhat resembles a tuning fork having curved armsthat vibrate toward and away from each other at the free ends, and aboutan imaginary pivot diametrically opposite the slot, thus shaking thecontents of the fluid tubes attached to the outside of the cavity shell.The cylinder may be supported along the imaginary pivot, which is a partof the cylinder that does not vibrate.

It should be apparent that both cavitation resonators described abovevigorously agitate the fluid contents in the manner of shaking a sodacan, causing the material having a sufficiently low pressure—i.e., thegaseous constituents of the fluid—to be liberated and drawn off intostorage receptacles or fed to a pollution prevention trap (to bedescribed), as shown in FIG. 3. One suitable piezoelectric material isknown as “Navy Type III,” and the unit may operate in either a 3-1 modeor a 3-3 mode for piezoelectric transducers. In either case, the unitsmay be kept cool by air flow or thermoelectric coolers added to thephase separator surface. As is well known, a thermoelectric cooler istypically a solid state “thermoelectric” device that may be used to“pump” heat away from one side of the device to another side when avoltage of the correct polarity is applied across the device. As thecharge carriers in the device move under the influence of the appliedvoltage, heat is also transported away from a hot region of the device,which is in thermal contact with the CPS to a cooler region of thethermoelectric device.

Referring to FIG. 9, there is illustrated a simplified perspective viewof a cavitation phase separator according to the present invention foruse in the embodiment of FIG. 3. The cavitation phase separator 500includes a cavitation chamber 502, a fluid inlet 504 coupled to thecavitation chamber 502 via a flexible tubing 506, and a fluid outlet508, similarly coupled to the cavitation chamber 502 through a flexibletubing 510. The fluid 524 enters the chamber 502, where it is subject tovigorous shaking forces applied by a transducer 520 through a saddle522. Fluid 526 that is substantially free of gases released by thecavitation action emerges from the outlet 508. Gases released by thecavitation action pass through ports 512 into a manifold 514 and arewithdrawn from the manifold outlet 516 as free gases 528. The releasedgases may include vapors that responded to the cavitation action causedby the transducer 520.

FIG. 9 is provided to illustrate an elementary structure that applies avigorous shaking force to a body of fluid or liquid substance, causingcavitation in the fluid or liquid of sufficient activity to cause therelease of gases mixed—i.e., not chemically bound—in the fluid orliquid. The transducer 520 may be of any type that is capable ofapplying the appropriate vibrating force at a suitable frequency to anenclosure or chamber 502 containing the fluid or liquid 524. In thefigure, a saddle component 522 may be used to couple the vibration ofthe transducer 520 to the chamber 502 containing the fluid or liquid524. As is readily appreciated by persons skilled in the art, the wallsof the chamber 502 must be sufficiently light-weight and stiff toefficiently impart the vibration force to the fluid or liquid 524 withinthe chamber 502. For example, the transducer 520 may be implemented byan electromagnetic device or motor. A loudspeaker is such a device,wherein an electromagnetic motor causes an acoustic radiating surfacesuch as a light-weight conical or spherical or planar element coupled tothe motor to vibrate at a particular frequency or range of frequencies.The transducer 520 may also be implemented by a piezoelectric componentas described herein, which applies acoustic energy to the fluid orliquid 524 within the chamber 502. Mechanical transducers, such as arotating cam operating against the chamber held against the cam underthe tension of a spring may also be used, provided that it canefficiently sustain vibration of the chamber 502 at an appropriatefrequency.

In the following descriptions of FIGS. 10, 11, 12, and 13, thepiezoelectric cavitation phase separator will also be referred to as a“phase separator” or “PCPS,” associated with a reference number in thefigure being described. Referring to FIG. 10, there is illustrated asimplified perspective view of a portion of a first embodiment of apiezoelectric cavitation phase separator or PCPS 540 according to thepresent invention. The phase separator 540 in FIG. 10 is called adouble-shell resonator and employs a linear piezoelectric stack 570 thatmay operate in either a 3-3 mode or a 3-1 resonant mode. The cylindricalcavity 544 for this configuration, formed by first 542 and second 546double-walled “C” sections, includes a slot 572 through the wall of thecavity (from outside to inside diameter), and along each of two oppositesides of the cylinder 544, from end to end, forming two semicircularshells 542, 544 whose concave sides face each other. The two concave,semicircular shells 542, 544 are disposed relative to a commonlongitudinal axis in the view illustrated in FIG. 10. The longitudinalaxis is not shown in FIG. 10 but is aligned with the center of thecylinder formed by the semicircular shells 542, 544. The linearpiezoelectric stacks 570 (in this example three such stacks may be used,each resembling a stack of dominoes) are each shown oriented along andacross a diameter of the cavity 544. In the view shown in FIG. 10, thelinear piezoelectric stacks 570 are shown at right angles to the planecontaining the slots 572, although the particular diametric alignment ofthe stacks 570 may differ from the right angle as shown. The twosemicircular “sides,” the first and second “C” sections 542, 546 of thecylinder, respectively attached to the opposite ends of the stacks 570of piezoelectric resonators, vibrate toward and away from each other,alternately compressing and expanding the volume of the cavity, and thusshake the contents of the fluid tubes disposed within the double wallsof the first 542 and second 546 sides of the cavity 544.

Continuing with FIG. 10, the piezoelectric stacks 570 connect toopposite interior walls 548 of each first 542 and second 546 sides ofthe cavity 544 via insulating blocks 574 at each end of the stack 570.the insulating blocks 570 may include terminals for connectingelectrical wires for energizing the piezoelectric elements of the stack570. It is preferable that the stacks be energized synchronously, whichrequires that the stacks all become resonant at the same frequency. Thesynchronous operation will consume less energy and more efficiently andcompletely liberate the gas materials from the fluid substances. Thestacks 570 may be disposed at approximately uniform intervals throughthe length of the cavity 544. Each double-walled first 542 and second546 side of the cavity 544 includes a plurality of fluid tubes 560 (onlyone is shown in phantom in the figure) spaced substantially uniformlyaround the inside space of the double-walled sides 542, 546. Thelongitudinal axes of the fluid tubes 560 are parallel with thelongitudinal axis of the cavity 544. The fluid tubes 560 may besupported by respective first and second end bells 550, 552, whichenclose the space 578 within the double walls of the first 542 andsecond 546 sides, and also function as inlet and outlet (at the endopposite the inlet end visible in FIG. 10) fluid ports 562 for the fluidsubstances to enter and exit the PCPS 540. Each of the fluid tubes 560may be equipped with a plurality of gas orifices 564 along an upper sideof their cylindrical walls to permit the escape of gas molecules fromthe fluid that is being agitated by the stacks 570 when they areenergized. Coupled to the fluid ports 562 are flexible tubes 582, 586which interface between the fluid inlet 580 and outlet 584 tubescarrying the fluid to be processed in the PCPS 540.

Referring to FIG. 11, there is illustrated a cross section view of theembodiment of FIG. 10. Structures shown in FIG. 11 that are the same asthe structures described for FIG. 10 bear the same reference numbers. Inaddition, FIG. 11 illustrates the gas outlet manifolds 592 and the gasoutlet ports 590 that are not shown in FIG. 10. The gases released inthe PCPS 540 emerge through the gas orifices 564 into the space 578within the double walls, and then escape through the gas outlet ports590 into the gas outlet manifolds 592. The gas outlet manifolds 592preferably convey the gas to a storage device (not shown in FIG. 11).The gas outlet manifolds 592 may also function as cleaning ports,wherein cleaning materials may be introduced to flush the interiorportions of the PCPS 540 at maintenance intervals. The reference number594 indicates the kind of motion imparted to the first 542 and second546 sides of the PCPS 540 when the transducers 570 are energized. Thismotion is generally and primarily back-and-forth along a longitudinalaxis of the piezoelectric stack The motion thus applied to the first 562and second 546 sides of the PCPS 540 imparts a vigorous shaking motionto the individual fluid tubes 560, causing sufficient cavitation torelease the gases 528 from the fluid 524.

Referring to FIG. 12, there is illustrated a simplified perspective viewof a portion of a second embodiment of a piezoelectric cavitation phaseseparator according to the present invention. This embodiment 600 of thePCPS may be called in this context a single shell or tuning forkresonator in which a transducer cylinder or body 602 includes a thinpiezoelectric layer 606. The transducer cylinder or body 602 is alaminated structure having nested layers including an outer shell 604,the piezoelectric layer 606, and an inner insulating layer 608. Thetransducer 602, which forms a cylindrical cavity within it, furtherincludes a single slot 640 disposed through the wall of the transducercylinder or body 602 and the piezoelectric lining from end-to-end,parallel to its longitudinal axis. The single slot 640 in effect definesfirst 642 and second 644 sides or halves of the cylindrical body 602.

The piezoelectric layer 606 is driven by an electrical signal appliedacross the piezoelectric layer through conducting wires 630, 632attached to conductive terminals 634 at a location on opposite sides oredges of the piezoelectric layer 606. An electrical drive signal ofsufficient amplitude and having a frequency sufficiently close to theresonant frequency of the transducer 606 is applied through theconnecting wires 630, 632. The transducer 606 is configured to vibratesuch that the free edges of the piezoelectric layer on either side ofthe gap 640 alternately increase and decrease the width of the gap atthe frequency of resonance, causing the two halves of the cylindricalwall to vibrate and shake the contents of the fluid tubes 612.Cavitation occurs, releasing the gas from the fluid. Thus, in crosssection as seen in FIG. 13, the transducer 602 resembles a tuning forkhaving curved arms or sides 642, 644 that vibrate toward and away fromeach other at the free ends adjacent the slot 640, and about a fixedpivot axis 648 diametrically opposite the slot 640, thus shaking thecontents of the fluid tubes 612 attached to the outside of the shell ofthe transducer cylinder 602. The cylinder 602 may be supported on a base610 along the fixed pivot axis 648, which is a part of the cylinder 602that does not vibrate. Like the embodiment described in FIGS. 10 and 11,the cylindrical body of the PCPS 600 functions as the transducer thatimparts the shaking forces to the fluid enclosed within the plurality offluid tubes 612. The fluid tubes 612 are preferably attached to thetransducer cylinder 602 with their longitudinal axes parallel with thelongitudinal axis of the transducer cylinder 602.

Continuing with FIG. 12, the fluid tubes 612 include a plurality ofports 614 leading into a manifold 616. Gases 676 released by thecavitation action emerge from an outlet 618, which may be coupled to aconduit leading to a storage device (not shown). Coupled to fluid ports620 of each fluid tube 612 are flexible tubes 662, 666 which interfacebetween the fluid inlet pipe 660 and the fluid tube 612 and between thefluid tube 612 and the outlet pipe 664. The fluid 670 entering the PCPS600 for phase separation by cavitation passes the fluid 670 to beprocessed in the PCPS 600 through the fluid tubes 612, gives up the gascontent through the orifices 614, and passes along the processed fluid672 through the flexible tube 666 and the fluid outlet pipe 664 to bestored.

Referring to FIG. 13, there is illustrated a cross section view of theembodiment of FIG. 12. Structures shown in FIG. 13 that are the same asthe structures described for FIG. 12 bear the same reference numbers.FIG. 13 also includes two manifold assemblies consisting of the fluidtube 612, a plurality of gas ports 614, and a gas manifold 616. One suchmanifold assembly is shown attached to an outer surface of each arm orside 642, 644 of the transducer 602. In addition, the reference number646 indicates the kind of vibrating motion imparted to the of the PCPS600 when the transducer 606 is energized. This motion resembles alow-amplitude vibration of the arms or sides 642, 644 about the fixedpivot axis 648, wherein the arms, corresponding to the sides 642, 644 ofthe cylinder 602 on either side of the gap 640, are curved as depictedin FIGS. 12 and 13. The motion thus applied to sides of the PCPS 600imparts a vigorous shaking motion to the individual fluid tubes 612,causing sufficient cavitation to release the gases 676 from the fluidentering the fluid ports 620.

The Pollution Trap

As described herein above, the geothermal fluid produced from the earthis processed in a cavitation phase separator to remove gas phasesubstances from the fluid that will be used to convey heat energy intothe renewable energy power plant system. In another step in processingthe gas and vapor substances, these materials may be fed to a pollutionprevention trap to separate the various different gases that may bepresent in the substances removed by the phase separator. The pollutionprevention (“P2”) cold trap included in FIGS. 3 and 14 (See P2 trap 106and 700, respectively) is a well known device and thus will only bebriefly described herein.

Referring to FIG. 14, there is illustrated a simplified block diagram ofone embodiment of a pollution prevention cold trap for selectivelyrecycling gases separated from said demand fluid according to thepresent invention. A simplified structure of a P2 cold trap 700 is shownin FIG. 14. In operation, geothermal gases from the phase separator maybe stored in a pressurized tank 706 that serves as a reservoir. Thereservoir 706, which may be disposed at a top-most portion of thepollution trap vessel 702, enables the removal of heat from the storedgases using, e.g., a thermoelectric cooler 704, followed by condensationof various constituents of the geothermal gases such as radon 710,hydrocarbons 712, H₂S 714, CO₂ 716, etc. The gases, which tend tocondense at varying temperatures and which also vary as to specificgravity, become liquid and may be diverted or drained into separatecollection facilities. In this way, these materials, not needed in thepower plant system, may be removed from the working fluids andseparately contained for reuse, sale, recycling, etc.

In the renewable energy power plant described herein, the utilization ofgeothermal fluids for the thermal energy they bear, may be at leastpartially purified or cleansed through the CSP and the P2 trap processesdescribed herein above. These processes are not unlike solution miningprocesses in which water, with or without other chemicals, may be pumpedinto deep subsurface wells to cause minerals or other deposits to becomedissolved in the fluid, and the resulting leachate pumped to the surfacefor processing and recovery of the minerals or compounds of interestthat are dissolved therein. Thus, the geothermal fluid pumped from thedeep, hot deposits for use in the renewable energy power plant maycontain a variety of minerals that have commercial value. Even if theamount of any individual mineral recovered is insufficient to justify adedicated facility to mine it, the present system may neverthelessprovide sufficient recovery of minerals in the aggregate as a parasiticprocess because of the necessity of cleansing the geothermal fluid priorto use in the renewable energy power plant.

Concluding Remarks

While the invention has been shown in only one of its forms, it is notthus limited but is susceptible to various changes and modificationswithout departing from the spirit thereof.

In the foregoing description, a number of novel additional componentsare employed in new combinations to enhance the efficiency of a basicbinary cycle geothermal power plant. Among the new components are heatbalancers with construction and design features to enhance heat transferand introduce combustible gases into the working fluids; and phaseseparators that utilize cavitation as an efficient way to release gasesmixed in the geothermal solutions. Among the new processes put to newuses are the electrolysis system to convert wind or solar-generatedelectricity to hydrogen gas, a form of energy that may readily be storedin tanks for later uses; and the injection of controlled amounts ofcombustible gases into the working fluids of a binary cycle power plantto enhance the plant efficiency. The inventions described herein draw onthe technologies of geothermal power plants, electrolysis of water,steam turbine driven electric generators, hydrogen-fired steam boilers,cavitation systems, heat exchangers, programmable control systems,pollution prevention traps, etc., improving them and combining them innew ways to provide renewable energy power plants that are efficient andhave very low emissions and carbon footprints.

By way of illustration, the combination shown in FIG. 3 is intended toillustrate the basic principles of the concepts of the present inventionby showing the relationship of the various specific additionalcomponents. However, FIG. 3 is not necessarily a real operatingrenewable energy geothermal power plant. The components shown may beused in multiples (see, e.g., FIG. 5), depending on the number ofturbine-generator combinations and the number of points throughout thesystem that the heat balancing, hydrogen injection, and cavitation phaseseparation (CPS) units are required to obtain the maximum operatingefficiencies in a given application.

For example, in a system having three turbine generators, the inputworking fluid for each turbine may be subject to heat balancing andhydrogen injection. In other flow paths of working fluid, heat balancingsteps may be used to advantage to optimize the temperature of the fluidin a particular path depending on its utilization. In another example,several turbine generating systems having varying capacities and/or evendifferent heat energy sources may be combined to better adapt theoverall system to changes in loading or variations in the availabilityof renewable energy resources. In one example, a first generator in thesystem may be optimized for a 1 to 10 Megawatt output. A secondgenerator in the system may be optimized to produce an output rangingfrom 10 to 25 Megawatts. A third component generator in the system may,accordingly, be configured to optimally generate 25 to 100 Megawatts.FIG. 5 is presented herein above to illustrate on such embodiment.Moreover, each turbine generating component may employ a particularcombination of heat balancing, heat sources, hydrogen injection, etc. tooptimize its operation at the most efficient capacity. In anotherexample, electricity may be generated from an alternative renewablesource to the wind power generating system described herein.

Solar energy conversion, or even generation from ocean wave action aretwo possible alternatives for generating electricity to supply theelectrolysis plant for producing hydrogen gas to be used in the variousways described herein above. In this way the power plant systemsdescribed herein above may be adapted to a wide variety of geographical,economical, environmental, and regulatory circumstances, withinsufficient proximity to geothermal and wind or solar generatingresources and electric power distribution networks. It is to be expectedthat, because of geographical and meteorological variations around theplanet, that different combinations of the renewable and supplementalenergy sources will be needed to fully and efficiently exploit therenewable energy resources available in specific locales.

Further, in some facilities, the fluid being returned to the injectionwell may be adjusted in temperature by heat balancing to facilitateinjection into and maintain the temperature of the receiving strata. Thesame geologic receiving strata may physically be used to store heatbecause the insulating properties of the hot dry rock will allow fortemperature storage of selected materials at extremely hightemperatures, even approaching the thermal limit of the outputs of theboiler and the gas turbine. The hot materials may be pumped intoselective directional holes drilled into the geothermal structure forenergy storage and heat gathering.

Moreover, the system of the present invention offers a number ofopportunities to recover minerals, gases, and other substances havingcommercial value through judicious application of the cavitation phaseseparator, P2 traps, precipitation basins, and associated devices,perhaps along with a solution mining unit and subsequent processingsteps as outlined.

1. A renewable energy electric power plant utilizing a steam-driventurbine generator, comprising: a hydrogen-fired boiler to produce steamto supplement a geothermal fluid to increase heat energy of a workingfluid driving said turbine generator; an electrolysis plant to producehydrogen gas to fire the boiler; a wind powered generator to produceelectricity to operate the electrolysis plant; a heat balancer havingseparate, interleaved passages configured for counterflow operation fortransferring heat between said steam from said boiler entering andflowing in one direction through said heat balancer and said workingfluid entering and flowing in the opposite direction within said heatbalancer; and a hydrogen injection manifold for injecting hot hydrogengas from said electrolysis plant into said working fluid to regulate theenergy density of said working fluid.
 2. The power plant of claim 1,further comprising: a heat exchanger for transferring heat energy fromsaid geothermal fluid to said working fluid wherein a portion of heatenergy of said working fluid originated from geothermal fluid extractedfrom a production well.
 3. The power plant of claim 1, furthercomprising: a cavitation phase separator configured with at least onepiezoelectric transducer for inducing said cavitation in said geothermalfluid flowing through said phase separator.
 4. The power plant of claim3, wherein said cavitation separator comprises: a double shell bodyhaving opposing half-cylindrical shells enclosing a substantiallycylindrical volume there between; at least one stacked piezoelectricresonating component coupled along a diameter of said substantiallycylindrical volume, said diameter bisecting said half-cylindricalshells; and at least one elongated fluid conduit attached to an outersurface of each said shell, oriented parallel with a longitudinal axisof said cylindrical volume.
 5. The power plant of claim 3, wherein saidcavitation separator comprises: a cylindrical shell, splitlongitudinally along one side of said shell forming thereby alongitudinal gap therein, said shell enclosing a substantiallycylindrical volume there within; a thin layer of piezoelectric materiallaminated to an interior wall of said shell; and at least one elongatedfluid conduit attached to an outer surface of said shell on either sideof said longitudinal gap, each such conduit oriented parallel with alongitudinal axis of said cylindrical volume.
 6. The power plant ofclaim 1, further comprising: a plurality of heat balancers, each saidheat balancer having separate, interleaved passages configured forcounterflow operation for transferring heat between a source side fluidflowing in one direction and a demand side fluid flowing in the oppositedirection within said heat balancer; wherein each said heat balancer ispositioned to balance the heat energy input to said demand side fluid ofa dedicated one of a plurality of turbine generators.
 7. The power plantof claim 1, further comprising: a control system including: a firstnetwork of input sensors disposed at first selected locations in saidsystem for monitoring operating parameters; a second network of controldevices disposed at second selected locations in said system forcontrolling said operating parameters; and a programmable computersystem in communication with said first and second networks to receiveinput signals from said first network and to send commands to saidsecond network for executing control actions in said second network inreal time.
 8. The power plant of claim 7, further comprising: anexecutable program set operatively coupled to said programmablecomputing system, for responding to status data regarding the demand forelectricity and the supply of renewable energy sources, and a range ofpreset operating points for maintaining an operating balance thatoptimizes efficiency of said renewable energy power plant.